Object name truncated for source file with multiple extensions

[ryan-phillips]

When a source file name is converted to an object file name, up to two extensions are removed from the end of the file name. For example, hello.x.c is output to hello.o by the gnu toolset.

Furthermore, the checks for conflicting file names is performed before the second extension is removed, so bakefile will not recognize that hello.x.c and hello.y.c both compile to the same object.

[vslavik]

Closed in favour of #79. Please don’t create duplicate issues, one (the PR itself) is just fine.